\begin{tabular}{ll}
A+B$-$AB; & A,B $>$ 0 \\
A+B+AB;   & A,B $<$ 0 \\
$\dfrac {A + B} {1 - \textup{min}( \lvert A \rvert, \lvert B \rvert )}$; & otherwise \\
\end{tabular}
